Instrumentation & controls provides rotary actuators,based on either hydraulic or pneumatic signal, in a wide range of torque angles. Torque angles in excess of 120° are not readily available with conventional cylinder and pivot, lever arrangements. These can be available with torque cylinders providing fully rotary operations. Two directly opposed cylinders are fitted to a central mounting block. A high gauge slotted piston rod passed through the block serves to unite the two associated piston heads. The slot in the piston rod has toothed rack [machined in it] which engages with the teeth of a pinion. The pinion and its shaft are made in one piece or joined together and are supported by bronze bearings located in the mounting block. Both ends of the shaft protrude out from the block. It working principle is when pressure is applied to one of the pistons, power is transmitted via rack and pinion to the shaft; thus the linear motion of piston and rack is converted to rotary motion of pinion and a shaft. The angle through which the shaft rotates is dependent upon the length of stroke of the piston. When pressure is applied to the opposing piston, rotation of the shaft occurs in the opposite direction. Torque momentum developed is dependent upon applied feed pressure, which may be varied as required. These actuators are available for various torque angles from 60° to 360°. The torque ranges with various models, up to 30,000 in-lb at 1,500 psi oil pressure in hydraulic actuators and 15,000 in-lb at 100psi air pressure in pneumatic actuators.
